Two SPI masters with a single SPI slave

[veerubiji]

Hi nickagian,
first of all sorry for confusion posting and also thank you very much for replying. i am using evb90129 evalution board,in that board mlx90129 ic and one light sensor and external temp sensor and trimmer sensor is there and mlx90129 having internal temp sensor also.mlx 90129 act as a standard lone data logger i think you also that one. it can communicate two ways one is rfid reader and another way is spi communication. i am using spi communication to read sensor values, for that i am using ATMEGA168 microcontoller, i am sending commands through hyperteminal communication.(i mean i connected my pc to microcontroller by using usb port,in my pc i am using hyperteminal to send spi commands), and i connected microcontroler to mlx90129 by using CON1_SPI you can see in data sheet also. mlx acts as a standerd alone datalogger so i set the configuration and i read the sensed values from mlx. that evb 90129 having external spi eeprom (128kB) if we want we can use that external memory in datalogging mode. i am reading values form mlx but when i am using external memory as my destination adress then i can read values so i need help which commands is used to read external memory.if you see the data sheet you can understand easily.i am sending my datasheets also.
best regards,
veerubiji.

 

[veerubiji]

hi,
can you suggest me is there any other 13.56MHz sensor tag /datalogger IC, not mlx90129 IC. or any other single chip datalogger IC's.
best regards.
thank you.

 

[nickagian]

Hi veerubiji,

Sorry for the delay answering you.

However I still don't understand what your problem is. I have understood that you want to save samples not only in the internal EEPROM of MLX90129 but also to use the external EEPROM of the EVB90129. So, concerning what commands you need help?

(1) The commands that you should send from the RFID reader to read data from the memory?
(2) Or the commands that the MLX90129 should send to the external EEPROM in order to read/write from/to it?

Please clarify. But in any case, for getting an answer to option (1) you could check yourself pages 19-25 of the data-sheet of the MLX90129 for the custom commands supported by the chip. For example for reading a word from an external memory via SPI you should send the command "Read external memory" with code A41F from the reader to the tag.

Nikos

 

[veerubiji]

hi,
thank you for replying, i am asking both rfid and spi commands are same ? and i am not using rfid communication so still i didnt chek rfid commands . i am using spi communication with that evb90129 board so i am reading the samples from mlx90129 chip. when i am setting in automatic logging mode and i am setting configuration store sample values in external memory, that is cat25128 so now i have problem reading samples from that external memory. can you explain which commands is used? and also i need commands mlx90129 should read and write from external memory.

 

[nickagian]

hi,
thank you for replying, i am asking both rfid and spi commands are same ? and i am not using rfid communication so still i didnt chek rfid commands . i am using spi communication with that evb90129 board so i am reading the samples from mlx90129 chip. when i am setting in automatic logging mode and i am setting configuration store sample values in external memory, that is cat25128 so now i have problem reading samples from that external memory. can you explain which commands is used? and also i need commands mlx90129 should read and write from external memory.

Hi,

for the commands that you should use from your microcontroller to read from the external SPI memory, you should download the cat25128 data-sheet (https://www.onsemi.com/pub_link/Collateral/CAT25128-D.PDF). Everything is found in there.

For example, to read from the memory you should follow figure 9 of the datasheet :

(1) first send the op-code for the read command (0x03)
(2) and then send the byte address of the first location on memory that you want to read.

Read the data-sheet extensively and follow the figures in detail for any other communication with the memory.

Nikos

 

[veerubiji]

Hi,
thank you very much for providing solution. and i read the data sheet i understand we need to write enable (0x06) frist then only you can write or read data from external memory. i have a problem on how to enable? i have to enable any adress or any thing? for example writing data to external memory is writing opcode 0x02 and 16 bit adress and data. like that is any format to enable that pin.
thank you.